Recently, a vehicle equips an air bag apparatus at front portion thereof (on a driver seat or on a passenger seat) for improving safety on a collision. When the vehicle crashes into an object due to an accident, the air bag apparatus outputs a signal (an operation signal) to an air bag actuator based on a signal from the collision-detecting sensor for actuating an inflator and inflating the air bag instantaneously.
On this account, for improving the safety on the vehicle collision, a vehicle having a function for switching a place where the air bag is inflated considering a direction of the impact due to the vehicle collision has been on a market. In this case, the air bag needs to be actuated based on an accurate determination whether or not a passenger is sitting on the vehicle seat. The judge whether or not the passenger is sitting on the vehicle seat, especially on the passenger seat, needs to be done more precisely because such seat may be variously occupied by a adult, a children or a baby on a child seat (Child Restraint System, hereinafter referred to as CRS).
Known seating detectors are disclosed in JP2000-301980A2, JP2001-201412A2, JP2003-80989A2 and JP2002-87132A2.
In JP2000-301980A2 and JP2001-201412A2, the known seating detector proposes a method of a pattern matching for determining a characteristic difference between a CRS and human by examining pressure distribution patterns of each occupant. In JP2003-80989A2, the known seating detector proposes a method for determining a characteristic difference between a CRS and human by examining distances among each peak seating pressures.
In JP2002-87132A2, a known method for determining the occupant is disclosed. Such method determines types of occupant by means of a seating area (total load), template matching, and edges obtained by summing up load differences between the sensors. The values of the total load when the vehicle seat is occupied by the CRS are similar to the values of the total load and the width when the vehicle seat is occupied by an adult or a child, however, according to the template matching, a characteristic of the vehicle seat on which the CRS is attached is different from a characteristic of the vehicle seat which is occupied by human. In addition, according to the edge detection, an edge amount when the vehicle seat is occupied by the CRS is different from an edge amount when the vehicle seat is occupied by human. Thus, the CRS may be misclassified as human when the total load applied to the vehicle seat is relatively large due to a load applied to the vehicle seat when the seat belt is fastening tightly. To improve the detecting accuracy when a high load is applied to the vehicle seat, the template matching and the edge detection are applied to the seat detector.
According to the known seating detector disclosed in JP2000-301980A2 and JP2001-201412A2, the occupant may be misclassified when a shape of a bottom portion of the CRS is similar to a hip shape of human body because a calculated value of the pattern matching when the seat is occupied by the CRS becomes similar to a calculated value of human.
According to the known seating detector disclosed in JP2003-80989A2 the occupant may also be misclassified when the shape of the bottom portion of the CRS is similar to the hip shape of human body because a distance among each peak seating pressure when the seat is occupied by the CRS becomes similar to a distance of human.
According to the known seating detector disclosed in JP2002-87132A2, the occupant may also be misclassified when the shape of the bottom portion of the CRS is similar to the hip shape of human body. In addition, the occupant may be misclassified when a result of the template matching when the CRS is attached on the vehicle seat is similar to a result of the template matching when human is seating on the vehicle seat. Further, when the CRS includes a bottom whose shape cause a small pressure difference on the edge thereof, so that the detecting accuracy may be decreased.
Thus, a need exists for a seating detector to determine whether the seat is occupied by human or occupied by a CRS accurately.